Few exercises carry as much baggage as the quarter squat. Old-school coaches swore by it; much modern commentary treats it as an ego lift. Both camps are partly right, which is exactly why it deserves a careful look: what Starr actually said, what the studies actually found, and how to program the lift if you decide it belongs in your plan.
What Counts as a Quarter Squat?
Squat-depth terms are looser than most lifters realize. Starr opened his discussion by pointing out that what most people call a half squat is, in practice, a quarter squat — so he simply used the latter term (pp. 81–82). Modern research defines the zones by knee angle: full squats pass roughly 100 degrees, half squats sit around 70–100 degrees, and quarter squats occupy roughly 40–60 degrees. In practical terms, Starr’s version meant descending about eight to ten inches from the standing position — noticeably lower than most lifters expect from the name.
Why Starr Used Them: Overload
The logic is the overload principle: muscles adapt to loads beyond what they are accustomed to handling. Shortening the range of motion lets a lifter handle substantially heavier weight through the strongest portion of the lift. Starr put it directly: “One of the best ways to overload the muscles of the legs and hips is by doing heavy half or quarter squats” (p. 81). Starr’s own numbers make the point: a lifter who could full squat 250 pounds for ten repetitions, 300 for five, or 325 for three could handle “in excess of 400” pounds in the quarter squat. That overload, he argued, builds a great deal of strength in the hip area — which he called the center of power for any athlete (p. 81).
But he attached a hard condition, and it matters: quarter squats are an advanced-trainee movement. Starting too soon, before the muscles supporting the lower back, knees, and hips have been strengthened by long stretches of demanding full squatting, invites problems the lift cannot protect you from (pp. 81–82).
The Mechanism: Joint-Angle Specificity
The training-science rationale behind Starr’s practice is called joint-angle specificity: strength adaptations concentrate at or near the joint angles you train. A partial squat lets you load the top-end hip and knee extension positions — the ones that matter for sprinting and jumping — with far more weight than a full squat permits. The trade-off is equally real: reduced range of motion means less total muscle involvement and less stimulus for general muscle growth than full-depth work provides.
What the Research Shows
Two frequently cited studies frame the debate, and they disagree:
| Study | Design | Key finding | Limitations |
|---|---|---|---|
| Rhea et al., 2016, Human Movement | 28 trained men, 16 weeks; quarter vs half vs full squat groups at equal relative loads | All groups improved their own depth’s 1RM; the quarter group showed the greatest transfer to vertical jump and 40-yard sprint performance | Small sample; prior training history undisclosed; quarter group handled higher absolute loads by design |
| Hartmann et al., 2012, J Strength Cond Res | 10-week intervention; deep front squat vs deep back squat vs quarter squat plus control group | Deep-squat groups improved squat- and countermovement-jump performance; the quarter group improved its own 1RM but showed no jump improvement and declines in maximal isometric strength and rate of force development | Performance-focused outcomes; specific to untrained-to-moderately-trained subjects |
A reasonable reading of both: quarter squats can add genuine overload at strong athletic angles, and may transfer to sprinting and jumping for well-prepared athletes — but they do not replace full squats for general strength, muscle growth, or all-round development, and the transfer evidence is mixed rather than settled. Treat either extreme claim (“useless” or “superior”) as unsupported. Practitioner experience points the same direction: NBA-strength coach Paul Fabritz has described reserving harder quarter-squat variations for athletes who already handle roughly one-and-a-half to two times bodyweight in squatting — a gatekeeping idea consistent with Starr’s advanced-only rule.
Programming Them the Starr Way
Starr folded quarter squats into his squat programming in three documented ways: replacing one of the higher-repetition squat days (the tens, fives, or threes — one of them, not all); following a normal session with additional quarter-squat work; or taking two or three sets of full squats first and continuing with five sets of quarters, letting the full squats act as a warm-up for the overload. His worked example for a lifter who handles 300 for five:
| Lift | Sets and reps |
|---|---|
| Full squats (warm-up) | 135×5, 185×5, 250×5 |
| Quarter squats | 300×5, 325×5, 350×5, 375×5, 400×5 |
Keep the repetitions at five, he advised — anything less does not build the reserve this movement exists for. Expect the workload to linger: extra rest between heavy sessions is often necessary after these workouts. For context on where sessions like this fit inside a weekly plan, see our pages on the original Big Three 5×5 and its heavy-light-medium loading.
Setup and Safety
- Use a power rack when possible. Starr considered rack pinning the safest way to train the lift: descend until the bar touches the pins set at your chosen depth.
- No bench underneath. A bench sits at a different height for everyone, encourages reaching for it with the hips, and relaxes the lower back at exactly the wrong moment.
- If you must lift outside a rack, spotters must be capable and close.
- Stay tight and upright, take short careful steps back, and control every descent — go as low as you can without sticking, and accept that your working depth will shorten as the bar gets heavier.
Who Should Skip Them
Beginners and intermediates without a substantial full-squat foundation should not touch this lift yet — Starr’s warning was explicit that premature quarter squatting invites trouble no amount of enthusiasm offsets. Build the base with full squats first (our overview of Starr-approved squat variations and the companion piece on timed squat methods cover that groundwork). Lifters chasing maximum muscle growth should also note that full-range squatting remains the better stimulus per the research above.
Frequently Asked Questions
How deep is a quarter squat?
Roughly a 40–60 degree knee angle in the research convention — in practice, about eight to ten inches of descent from standing, by Starr’s description.
Do quarter squats improve vertical jump?
The evidence splits. One 16-week trained-athlete study found the greatest sprint and jump transfer from quarter-squat training; another found no jump improvement and some declines in explosive-strength measures after quarter-squat-only training. The honest summary: possibly, for well-prepared athletes, as a supplement to — not a replacement for — full squatting. Our vertical-jump plyometrics guide covers the complementary training side.
Are quarter squats bad for your knees?
The cited studies measured performance, not injury rates, so neither supports a blanket verdict in either direction. Starr’s own safety conditions were preparation (advanced full-squat background), a power rack or competent spotters, controlled descents, and honest loading — follow those and you are following the published guidance.
Quarter squats or full squats?
Both, in the right proportions. Full squats build the foundation and the muscle; quarter squats overload the top end for advanced lifters who need it. Starr used them together, and the research gives no reason to abandon either role. Explosive lifters rounding out their power work will also benefit from his quick-lifts guide.
Sources
Primary: Bill Starr, The Strongest Shall Survive: Strength Training for Football, pp. 81–82 (quarter-squat passage). Research: Rhea, M.R., et al., “Joint-Angle Specific Strength Adaptations Influence Improvements in Power in Highly Trained Athletes,” Human Movement 17(1):43–49, 2016, doi:10.1515/humo-2016-0006; Hartmann, H., et al., “Influence of Squatting Depth on Jumping Performance,” Journal of Strength and Conditioning Research 26(12):3243–3261, 2012. Context: Sigma Nutrition’s methodological critique of the Rhea study; Men’s Health interview with coach Paul Fabritz (practical readiness thresholds).
Last updated: August 2026 · Edited presentation combining Bill Starr’s published guidance with summarized research — not newly written by Bill Starr.
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